The invention relates to quick-opening valves of the rupturable-diaphragm type and more particularly to the explosive shearing of closure diaphragms to produce fragment-free openings therein.
Rupturable diaphragm valves find use in numerous fields. Such valves have traditionally been used for the protection of pressure vessel and other equipment wherein a dome-shaped, frangible diaphragm ruptures at a predetermined pressure. These valves are also used to produce an instantaneous flow of high-velocity gas, such as in a shock tunnel to study the reaction of aerodynamic shapes in high-speed air flows. Another use of such devices is to seal a compartment, such as in a submerged weapon or other marine hardware, and then to flood the compartment at some later time.
The traditional rupture valves are not entirely satisfactory in a variety of uses because they are designed to rupture at a predetermined pressure differential and not at the command of an operator. Furthermore, small variations in rupture pressures between individual diaphragm and the inability to confine the fluid at the desired rupture pressure for a period of time prior to release, have rendered such valves unsuitable for many purposes.
Techniques to increase the degree of control over the bursting of the diaphragm include the use of electromechanical or explosive means to punch out an opening in the diaphragm. Mechanical diaphragm piercing means, however, are bulky, occupying critically-needed space, and the response time is too slow for certain applications. Examples of the explosive rupturing of diaphragms are shown in U.S. Pat. No. 3,109,553, issued Nov. 5, 1963 to Fike and U.S. Pat. No. 3,469,733, issued Sept. 30, 1969 to Montgomery et al. The device of Fike has not proved altogether satisfactory in use since the edges of the diaphragm tend to curl inward toward the concave side, preventing complete opening and obstructing the flow past the diaphragm. In the patent to Montgomery et al, an explosive charge in flat sheet form is cut into a pattern and converted into a U-shaped groove or score marks on the diaphragm defining the opening. The arrangement of the explosive material relative to the grooves produces a tearing action along these marks when the explosive is initiated.
Similar devices are shown in U.S. Pat. Nos. 3,267,662 to Miller and 3,437,035 to Weimholt, wherein the explosive materials are placed in grooves on a backing element which in turn is mechanically fastened to the diaphragm. The flap opening arrangement of Arnold et al in U.S. Pat. No. 3,777,772 incorporates a weakening groove in the diaphragm with the explosive material in a grooved backing element. All of these explosive methods, however, tend to produce small fragments and splits due to the tearing action that occurs. High velocity fragment are detrimental in many applications. Additionally, this method does not make efficient use of the explosive charge since a tearing action require more force than a positive shearing action. Consequently, with increased pressure and diaphragm thickness, disproportionate increased amounts of explosive material are required for diaphragm rupture.